add log to file feature

crates/bevy_log/Cargo.toml

@@ -9,7 +9,7 @@ license = "MIT OR Apache-2.0"
 keywords = ["bevy"]
 
 [features]
-trace = [ "tracing-error" ]
+trace = ["tracing-error"]
 
 [dependencies]
 bevy_app = { path = "../bevy_app", version = "0.9.0" }
@@ -21,6 +21,7 @@ tracing-chrome = { version = "0.7.0", optional = true }
 tracing-tracy = { version = "0.10.0", optional = true }
 tracing-log = "0.1.2"
 tracing-error = { version = "0.2.0", optional = true }
+tracing-appender = { version = "0.2.2" }
 
 [target.'cfg(target_os = "android")'.dependencies]
 android_log-sys = "0.2.0"

crates/bevy_log/src/lib.rs

@@ -14,6 +14,8 @@
 #[cfg(feature = "trace")]
 use std::panic;
 
+use std::path::PathBuf;
+
 #[cfg(target_os = "android")]
 mod android_tracing;
 
@@ -25,6 +27,7 @@ pub mod prelude {
  };
 }
 
+use bevy_ecs::system::Resource;
 pub use bevy_utils::tracing::{
  debug, debug_span, error, error_span, info, info_span, trace, trace_span, warn, warn_span,
  Level,
@@ -91,13 +94,70 @@ pub struct LogPlugin {
  /// Filters out logs that are "less than" the given level.
  /// This can be further filtered using the `filter` setting.
  pub level: Level,
+
+ /// Configure file Logging
+ pub file_appender_settings: Option<FileAppenderSettings>,
 }
 
 impl Default for LogPlugin {
  fn default() -> Self {
  Self {
  filter: "wgpu=error".to_string(),
  level: Level::INFO,
+ file_appender_settings: None,
+ }
+ }
+}
+
+/// Enum to control how often a new log file will be created
+#[derive(Debug, Clone, Copy)]
+pub enum Rolling {
+ /// Creates a new file every minute and appends the date to the file name
+ /// Date format: YYYY-MM-DD-HH-mm
+ Minutely,
+ /// Creates a new file every hour and appends the date to the file name
+ /// Date format: YYYY-MM-DD-HH
+ Hourly,
+ /// Creates a new file every day and appends the date to the file name
+ /// Date format: YYYY-MM-DD
+ Daily,
+ /// Never creates a new file
+ Never,
+}
+
+impl Into<tracing_appender::rolling::Rotation> for Rolling {
+ fn into(self) -> tracing_appender::rolling::Rotation {
+ match self {
+ Rolling::Minutely => tracing_appender::rolling::Rotation::MINUTELY,
+ Rolling::Hourly => tracing_appender::rolling::Rotation::HOURLY,
+ Rolling::Daily => tracing_appender::rolling::Rotation::DAILY,
+ Rolling::Never => tracing_appender::rolling::Rotation::NEVER,
+ }
+ }
+}
+
+#[derive(Resource)]
+struct FileAppenderWorkerGuard(tracing_appender::non_blocking::WorkerGuard);
+
+/// Settings to control how to log to a file
+#[derive(Debug, Clone)]
+pub struct FileAppenderSettings {
+ /// Controls how often a new file will be created
+ pub rolling: Rolling,
+ /// The path of the directory where the log files will be added
+ ///
+ /// Defaults to the local directory
+ pub path: PathBuf,
+ /// The prefix added when creating a file
+ pub prefix: String,
+}
+
+impl Default for FileAppenderSettings {
+ fn default() -> Self {
+ Self {
+ rolling: Rolling::Never,
+ path: PathBuf::from("."),
+ prefix: String::from("log"),
  }
  }
 }
@@ -165,6 +225,28 @@ impl Plugin for LogPlugin {
 
  let subscriber = subscriber.with(fmt_layer);
 
+ let file_appender_layer = if let Some(file_output) = &self.file_appender_settings {
+ let file_appender = tracing_appender::rolling::RollingFileAppender::new(
+ file_output.rolling.into(),
+ &file_output.path,
+ &file_output.prefix,
+ );
+
+ let (non_blocking, worker_guard) = tracing_appender::non_blocking(file_appender);
+ // WARN We need to keep this somewhere so it doesn't get dropped.
+ // If it gets dropped then it will silently stop writing to the file
+ app.insert_resource(FileAppenderWorkerGuard(worker_guard));
+
+ let file_fmt_layer = tracing_subscriber::fmt::Layer::default()
+ .with_ansi(false)
+ .with_writer(non_blocking);
+
+ Some(file_fmt_layer)
+ } else {
+ None
+ };
+ let subscriber = subscriber.with(file_appender_layer);
+
  #[cfg(feature = "tracing-chrome")]
  let subscriber = subscriber.with(chrome_layer);
  #[cfg(feature = "tracing-tracy")]

examples/app/logs.rs

@@ -1,13 +1,15 @@
 //! This example illustrates how to use logs in bevy.
 
-use bevy::prelude::*;
+use bevy::{log::FileAppenderSettings, prelude::*};
 
 fn main() {
  App::new()
  .add_plugins(DefaultPlugins.set(bevy::log::LogPlugin {
  // Uncomment this to override the default log settings:
  // level: bevy::log::Level::TRACE,
  // filter: "wgpu=warn,bevy_ecs=info".to_string(),
+ // This will let you configure file logging
+ // file_appender_settings: Some(FileAppenderSettings::default()),
  ..default()
  }))
  .add_system(log_system)